This invention relates to electron beam devices and more particularly to means for effecting concentricity of a multi-electrode beam generating means within an encompassing portion of the envelopic enclosure thereof.
In electron beam devices, for example cathode ray tubes employed in image display devices such as television applications, resilient-type spacer positioners or snubber supports are conventionally utilized to space and align the electron generating and controlling assembly, or electron gun structure, within the neck portion of the enclosing envelope. Usually, three or more of these longitudinally-formed resilient snubber members are attached to the terminal electrode structure of the beam generating means, in a manner to extend forward and outward thereof, to contact the sidewall of the encompassing neck portion. These forwardly oriented projecting snubbers are intended to not only effect a degree of lateral support for the electron gun, but also provide an electrical connection between the gun structure and the electrical conductive coating commonly disposed on the interior surface of the funnel portion and extended therefrom into the neck portion to the region adjacent the forward part of the electron gun structure. It has been found that such forwardly extending snubbers, because of their lengthy resilient support arms and the individual placement thereof, provide a degree of concentric support for the electron gun structure that is often less than desired. Under certain shock conditions, the length of these protruding positioning members is apt to allow relative lateral motion of the electron gun with respect to the encompassing envelope. As a consequence, the alignment of the gun within the envelope may be temporarily out of specification, or possibly permanently misaligned, thereby detrimentally affecting the operational characteristics of the tube. Color cathode ray tubes in particular require precision alignment of the electron gun structure relative to the mask openings and the associated patterned screen. Therefore, it is prerequisite that the electron gun structure be concentrically aligned and maintained as such to insure optimum tube performance. Furthermore, particularly in short neck tubes, the forwardly oriented snubbers are apt to extend into a region critical to the desired operation of the tube, such as protruding into the yoke field, or be positioned so that they may become heated during getter flashing, or be oriented in a manner to effect shadowing of one or more of the electron beams closely passing thereby.